Annealing and other heat-treatment furnaces



Feb. 18, 1936. A. G. LOBLEY VANNELAJJINCT AND OTHER HEAT TREATMENT FURNACES 2 Sheets-Sheet l Filed Dec. 2o, 195s Feb. 18, 1936. A, G. LoBLEY ANNEALING AND OTHER HEAT TREATMENT FURNACES 2 Sheets-Sheet 2 Filed Dec. 20, 1933 Patented Feb. 1936 UNITEDv STATES AND OTHER HEAT-TREATMENT FURNAcEs l ANNEALING PATENT oEElrcE land, a, British company A v Application December 20, 1933,' Serial No. 703,260

In Great Britain'December 22, 1932v s claims. (ol. 26m) This inventionhas reference. to annealing and other heat-treatment. furnaces of the counterperformed in an atmosphereof reducing or proiiow recuperative type in which two trains of .worky (such as tubes, strips or the like) are mechanically conveyed, in opposite directions, through side-by-side systems of recuperative .chambers arranged' at opposite ends of the treatment chamber'or chambersi The said inventlm comprises improvements which 'are particularly applicable to and are hereinafterdescribed in their application to an electric bright-annealing furnace of the above mentionedtyp'e, in .which the heat-treatment is tective gas.

A furnace installation embodying improvements according to the invention issho'wn in the accompanying drawings, wherein j Figure 1-is a plan showing a'portion ofthe general arrangement of the installation. I

Figure 1A is a plan View of a portion of the continuation of the 'installation shown partially in Figure 1, this continuation extending in alinement from the right-hand end of the portionl shown in'Figure A1.4 T

Figure 2 is an enlarged-scale section-of. one of the mechanically-driven work-conveyor rollers which are arranged in two side-by-side tracks running from end to-end ofthe structure.; Y

- Figure 3 is a sectional. elevation, and

Figure 4a plan, of a gas-circulating fan such as is provided in each of the recuperative chambers, andV "f y,

Figure 5 is a view of a partjofthe mechanism provided for drivingthe work-conveyor rollers.

The same lettersof reference indicate corresponding parts in the vseveral figures of the drawings. 'Y ,i

The furnace installation as shown in Figure 1 comprises a central heat-treatmentchamber a arranged at opposite ends of, and comunicating with, the said treatment chamber a, whilst outwardsV of each of 'the recuperating chambers, there is, on the one side,- aseriesv of cooling chambers c c1; and, on theother side, a series of gas- .Y extreme ends of` the`, chamber-fsystem,and the Vseal or air-excludingchambers d d1, Loading and unloading tables e fe1,. are,` arranged at the structure provides for'. ance oftWo trains. o f chambers; the one'trainf'bemgj conveyed through the ygas-seal chamber'sj" ber b, the treatment v-chamberc ,the recuperative l"conn-ter-flow conveychamber b1, and thecooliiigchambers c1 on one`.jrollertracks, so that there is no obstrtion to rk hroughv the series of rectionfc travel of the other train.

he recuperative chamf side of the installation, whilst the other train is conveyed in the reverse direction through the gas-seal chambers d1, the recuperatlve chamber l b1, the treatment chamber a, the recuperative chamber b, and the. cooling chambers c on the `other side. The. worky trainsj are, conveyed. in this manner by two side-by-side and continuous tracks of live rollers p, p1 which are arranged on or above the oors of the successive chambers and are mechanically driven in opposite direc- 'tions as hereinafter described.

Theinstallation thus provides that, in each of thetwo recuperating chambers, a` train of hot work proceeding from the Itreatment chamber passes a-.train ofrelatively cold work proceeding into the. said 'treatment chamber to enable the pre-heating ofingoing work by the exchange of i heatA betweenthe counterflowingtrains.

1 Now one ofthe objects of the present invention is to `provide for such an accelerated exchange of heat between the out-goin@ and ing'oing work-trains that the iii-going work may be pre-heated to v temperatures substantially higher than are obtainable in recuperative systems wherein only the convective circulation of the hot gases-is relied upon for pre-heating' prposes; thisj object being realized under vthe said invention by the provision, "in a suitably-cona system of cased propeller-fans whichiare arvranged belowthe side-by-side conveyor @tracks and are adapted kto draw gas downwardly through the work on the one track, and force the. said gas upwardly through the work on the other and two series of recuperating chambers b, b1,y

Y arrows@V show the direction of travel ofthe one train of' work, and full-line arrows show the di- 'Injttiis installation, .each of the recuperating chambers b b1 is devoid of any longitudinal partition or wall in the zone above the side-by-side the transverse travel of gas in this supra-roller zone. In the floor of each chamber, a system of cased propeller fans f g is installed as shown in Figures 1, 3, and 4; the casing h of each fan being arranged below, and transversely to, the roller-tracks with its 'intake orifice h1 presented to the underside of one of the roller-tracks, and with its discharge orice hz presented to the underside of the other roller-track. Preferably, and as in the illustrated installation, the intake orifices of the fan casings are arranged under those rollers which are carrying hot work out of the treatment chamber, so that when the fans are in operation they will draw gas from the supra-roller zone, downwardly through the hot out-going work, and discharge gas upwardly through the in-going work, again into the unobstructed supra-roller zone, wherein the gas passes transversely over the work-trams in completing the fan-forced circulation. Longitudinal baille-walls i (see Figures 3 and.l 4) are preferably arranged to extend from the floor up to the rollers to prevent short-circuit travel of gas inthe infra--roller zones.

To obviate the necessity of providing internal bearings for the work-conveying rollers. such `as ofv the recuperating chambers,of structural obstructions to the transverse gas circulation, the 30 rollers of leach train are constructed, mounted and driven as shown in Figures 2 and 5. In fact, the whole of the rollers of a furnace installation such as hereinbefore described with reference to Figure 1 may advantageously be mounted and driven in the same manner,- since alldifliculties attending the lubrication and replacement of internal bearingfare thereby elim- `According to this feature of the invention, each of Vthe rolleis p, p1 in both conveyor-tracks is cantilever-mounted or supported in bearings only at its outer or driven end; the roller-shaft m1 being extended through a gas-sealed aperture in the side-wall of the furnace-casing and carried in a long and stii external bearing' m bracketed to a rigidly-constructed frame m2 lthat extends along the side of -the structure. 'Outwards of its bearing-bracket, each roller-shaft is furnished with a worm-wheel m3 and the worm-wheels of the, whole of the rollers pertaining to each rolltrack, are engaged. lto gear with a common wormshaft m4 that extends from end to end of the stnicture.

Each shaft and its complementary wormwheels preferably are enclosed in an oil-containing casing n fitted internally with oil-baths nl to provide for the adequate lubrication of the gear. Each driving shaft m4 is independently driven to enable the respective tracks of rollers to be rotated in opposite directions and either at thesame or at different speeds, according to the relative rates at which it maybe desired to convey work through the respective series of chambers.

To the roller-apertura o against gaspressible gas-impervious and refractory material may be pegged or otherwise secured to the outer wall of the furnace-casing so that it surrounds the roller-shaft and covers the aperture; and a second washer o2 made of metal may be arranged to bear upon the'outside of the compressible washer and be loaded by a suitablyapplied spring o3. y

The internal part of each roller may be constructed of a work-supporting sleeve or cylinder m5 of heat-resistant alloy-which, 'at its outer end, is shrunk upon and keyed to a steel driving shaft, and is plugged at the inner end m6; the interior of the sleeve being packed with heat-insulating powder so that loss 'of heat by conduction from the said sleeve to the shaft is redud to a minimum.

To prevent the travelling work contacting with f and damaging, or being damaged by, the interior Y L parts 'of the structure, internal rubbing plates n2 n3 are provided lto present smooth and continuous longitudinal surfaces to the sides of the work-trains. The plates n2 on the outer sides are apertured with clearance holes for, and may be held in position by, the rollers passing through rtheir apertures, whereas the plates 1i on the inner sides maybe suspended and positioned in relation to the unsupported ends ofthe said rollers by hangers n4 carried on longitudinal members arranged intermediate the vroller-tracks.

Where such hangers are used in the recuperating chambers, theyare so constructed and-disposed as to avoid material interference with the transverse circulation of gas in the supra-roller zones. Further, where the'treatment chamber is provided with roof-resistors arranged in longitudinal relation to the transverse rollers, 'the inner rubbing plates may be spended from longitudinal beams carried, by upright members which may ,also support the roof-resistors; the piers or bases of these members being utilized, if desired, to support and locate other systems of resistor elements underneath the said conveyorrollers. l

As a measure of precaution againstl stoppag of the 'work flow when charges are undergoing treatment, it may be arranged for the worm shafts of the two roller-driving gear systems to be, driven inopposite directions from a single el tro-motor through gearing which drives-the sai shafts in opposite directions and provides for the speed of either relation to that of the other. Two such motors and'gearings are, however, installed (as for example, on an overhead control platform q, Figure 1) as a precaution against the breakdown of either.

Havingl described my invention, what I claim and desire to secure by Letters Patent isz- 1. A heat treating furnace including a heating chamber, a recuperating chamber adjacent thereto, a pair of work-supporting conveyors extending through the recuperating chamber and spaced from the top and bottomv walls of said chamber to provide zones above and below said work-supporting conveyors, means for driving the work-supporting conveyors in opposite directions to move one train of work through the recuperating chamber and into the heating chamber and the other train of work from the heating chamber .through the recuperating chamber, and means in the recuperating chamber in one of said zones for forcibly extracting heat at one side ofsaidrecuperating chamhes'xm u 'shaft being Varied in work leaving the heating chamber and for forcibly discharging the said heat at the opposite side of the recuperating chamber onto the work entering the heating chamber, the zone on that side of the work-supporting conveyors opposite that containing the extracting and discharging means being substantially devoid of obstructions to gas circulation from the discharging to the extracting means.

2. A heat treating furnace including a heating chamber, a recuperating chamber adjacent thereto, a pair of work-supporting conveyors extending through the recuperating chamber and spaced from the top and bottom walls of said chamber to provide zones above and below said work-supporting conveyors; means for driving the work-supporting conveyors in opposite directions to move one train of work through the recuperating chamber and intothe heating chamber and the other train of work from the heating chamber through the recuperating chamber, and a fanhaving its intake orice in one of said zones and at one side 'of said recuperating chamber and arranged adjacent one of the worksupporting conveyors and its dischargel orifice in the same zone as that containing the intake orifice and at the opposite side of the recuperating chamber and arranged adjacent the other worksupporting conveyor, whereby the fan will extract through one train ofA workand will discharge through the other train to eect the exchange of heat between the oppositely-moving trains of work, the zone on that side of the worksupporting conveyor opposite that containing the intake and discharge oriiices of the fan being substantially devoid of obstructions to gas circulation from the discharge oriiice oi the fan to the intake oriices thereof.

3. A heat treating furnace ingv chamber, a recuperating chamber adjacent thereto, a pair of work-supporting conveyors extending through ,the recuperating chamber and spaced from the top of said chamber to form a Work-treating zone above the work-supporting conveyor, means for driving the work-supporting conveyors in opposite directions to move one train of work through theV recuperating chamber and into the heating chamber and the other train of work from the heating chamber through the recuperating chamber, and a fan having its intake orice arranged at one side of said recuperating chamber and disposed beneath the train of work leaving the heating chamber and its discharge oriiice arranged at the opposite side of said recuperating chamber and disposed beneath the train of work entering the heating chamber, to eect the exchange of heat between the oppositely-moving trains of work, the zone above the work-supporting conveyors being substantially devoid of obstructions to gas circulation from the discharge orifice to theintake orice of the fan.

4.'A heat-treating furnace including a heating chamber, a recuperating chamber adjacent thereto, 'a pair of work-supporting conveyors extending through the recuperating chamber and spaced from the top-of said chamber to form a `worktreating zone above the Work-supporting conveyors, means for driving the work-supporting conveyors in opposite directions to move one train of work through the` recuperating chamber and into the heating chamber and the other train including a 'heat-e l of work from the heating chamber through the recuperating chamber, and a fan mounted in the recuperating chamber and below the level of the work-supporting conveyors, said fan having its intake orifice arranged at one side of said recuperating chamber and disposed beneath the train of work leaving the heating chamber and its discharge orifice arranged at the opposite side of said recuperating chamber and disposed beneath the train of work entering the heating chamber, to effect the exchange of heat between the oppositely-moving trains of work, the zone above the work-supporting conveyors being substantially devoid of obstructions to gas circulation from the discharge oriiice to the intake orice of the fan.

5. A heat treating furnace including a heating chamber, a recuperating chamber adjacent thereto, a pair of work-supporting conveyors extending through the recuperating chamber in adjacent parallel relation, means for driving the work-supporting conveyors in opposite directions to ,move one train of work through the recuperating chamber and into the heating chamber and the other train of work from the heating chamber through the recuperating chamber, and a fan having its intake orice arranged below the worksupporting conveyor which moves the train of `work from the heating chamber and through the to permit the fan to set up an uninterrupted circulation transverse to the lines of travel of the conveyors to eiect the exchange of heat between i the oppositely-moving trains of work.

' its intake oriiice spaced below the work-supporting conveyor which moves the train of work from the heating chamber' and through the recuperating chamber and its discharge orice spaced below the work-supporting conveyor which moves the train of work through the recuperating chamber and into the heating chamber, the intake and discharge orifices of said fan being disposed in substantially the same plane `transverse to the lines of travel of the conveyors, the recuperating chamber being devoid of obstructions above said work-supporting conveyors to permit the fan to v set up an uninterrupted circulation transverse to the lines of travel of the conveyors, and a longitudinally-extending baille wall disposed beneath and between the conveyors to cause the circulation between the intake and discharge orices ofthe fan to pass above the conveyors.

A. GLYNNE LOBLEY. 

